The aim of this project is to implement and evaluate an advanced neuroprosthetic system for restoration of hand-arm function in human subjects who have sustained cervical level spinal cord injury. The neuroprosthesis will provide the person with C5 tetraplegia with control of grasp and release and elbow extension by electrical stimulation of the paralyzed muscles. These functions will enable the user to regain the versatile manipulative functions which will increase their ability to perform activities of daily living independently. The myoelectric control signal which provides the command input and the stimulation that activates the muscles will be implanted surgically. Thus, the user will be free from issues of sensor mounting and maintenance of cabling and connections to the leads and electrodes on the extremities. The neuroprosthesis to be implemented consists of an external control unit, a multichannel implanted stimulator-telemeter, and implanted electrodes which sense muscle activity (a myoelectric signal). The project will result in (1) completed fabrication of all implanted and external components of the advanced neuroprosthetic system, (2) enhancement of the outcome assessment techniques used to measure system performance, and (3) evaluation of its efficacy in five individuals. Outcome evaluations will measure the function of individual components of the neuroprosthesis and the performance of users in grasp-release tests and activities of daily living. These tests allow statistical comparisons of the user's abilities before surgery with those achieved after surgery, both with the neuroprosthesis turned on and turned off. The results of this project will demonstrate the feasibility of a totally implanted neuroprosthesis and the significant improvements in hand function achieved through its use. The long term objectives of this research are to provide innovative techniques for restoration of functional movement in persons with central nervous system disorders. This research will develop the fundamental modules of neuroprosthetic systems for restoration of control of movement and sensation and perform clinical research to demonstrate their feasibility. The proposed system also has application in the efforts to provide standing and walking in thoracic level spinal cord injury, stroke, and head injury. These types of applications have been considered in defining the proposed system, so that it will be versatile across different clinical applications.